# Will freezing water still expand width-wise in a pipe (possibly breaking it) if it's free to expand lengthwise?

Will freezing water still expand width-wise in a pipe (possibly breaking it) if it's free to expand lengthwise?

• It surely will, if the pipe is long enough and both ends get blocked by the ice. Jan 6 '16 at 5:21

It might do.

Imagine you have a U-shaped pipe. The two ends are above ground. The pipe runs into the ground for a short length in the middle, then back out again. It's free at both ends but filled with water.

You have a problem there because in cold temperatures, the two above-ground parts are going to freeze first. Then, if it's really cold, the underground part will freeze also. When that happens, the already-frozen above-ground ice won't move and your underground pipe may well go pop. What was initially "free at both ends" became blocked.

• So the pressure needed to move the blocking ice is greater than the pressure needed to bend/break the pipe?
– Matt
Jan 7 '16 at 0:38
• Strictly, it is going to depend the physical characteristics of the pipe material (e.g. elasticity, strength), its thickness and shape (e.g. opening vs closing funnel, further bends in the pipe), the amount of ice and any chemical bonding at the ice/pipe surface. I'm afraid I don't have figures to help you calculate it for any particular scenario. Jan 8 '16 at 14:17

Yes, if you do it right and this is indeed a technique used to maintain pipes see: 1,2.

That being said, there are obvious problems when you have two frozen chunks as ice in a pipe is able to withstand significant PSI without moving.

• What if the water is frozen by nature (i.e. the pipe is outside)?
– Matt
Jan 6 '16 at 16:05